Clogs are a common problem in any device in which flowable materials flow through narrow passages. Examples of devices in which clogs occur include drains of plumbing fixtures such as sinks, toilets, bathtubs and showers. Additional examples of devices in which clogs can occur are automobile radiators/cooling systems, heat exchangers and marine engine (outboard, inboard and inboard/outboard) cooling systems, especially those that use seawater for cooling.
One method for cleaning clogs in drains is using a cable drain tool (e.g., a snake). However, tools such as these may damage plumbing fixtures and may prove difficult to use in some situations such as sinks and bathtubs with drains having narrow passages and/or a series of bends. Another method for cleaning drains includes using chemicals including caustics and acids. This method has drawbacks in that the chemicals are highly detrimental to plumbing systems and plumbing fixtures and may cause personal injury and/or destroy metal fittings. Additionally, caustic chemicals may damage PVC pipes and acids may damage porcelain. Yet another method for cleaning clogs involves the use of high pressure devices that may rupture plumbing joints.
In order to address these problems, other methods and devices involving the sequential application of a series of pressure and vacuum pulses have been developed. These methods and devices are described in U.S. Pat. Nos. 5,664,284; 5,193,245; 5,105,504; and 4,933,017, the contents of which are hereby incorporated by reference herein. These methods and devices have proven successful in clearing clogs in a wide variety of applications. However, there is room for improvement in each of these methods and devices.
U.S. Pat. Nos. 5,105,504 and 4,933,017 describe devices that include a mechanism for varying the application of pressure and vacuum forces to a clogged drain that is remote from a hose through which the pressure/vacuum is applied to the drain. Although not apparent from these patents, it has been discovered that in many situations, especially those involving clogged drains in household plumbing fixtures, it is necessary as a practical matter for a first person to hold the hose in place over the clogged drain while a second person manipulates the mechanism to alternate the application of pressure and vacuum. The practical necessity for two people to practice the inventions taught in these patents increases the cost associated with the practice of those inventions.
U.S. Pat. No. 5,193,245, which is a continuation-in-part of the '504 and '017 patents, includes an embodiment depicted in FIGS. 4 and 5 with a trigger 76 located at an end of the hose that controls a solenoid 80 that moves a blade or damper in a control manifold that allows the operator to switch between a vacuum and a pressure position. While this embodiment may allow operation of the device by a single person, it too suffers from a drawback in that the solenoid valve only allows the operator to switch between full pressure and full vacuum. This can be problematic for two reasons. First, when using the device in a fragile environment such as an old plumbing system, it may be desirable to operate the device with only partial pressure and/or partial vacuum for some portion or all of the process. Second, even when full pressure or vacuum are to be used, it is often desirable to slowly build to full pressure or vacuum to avoid shock to fragile systems and/or to avoid agitating waste in, for example, a clogged toilet bowl. The embodiment of FIGS. 4 and 5 do not allow an operator to remotely control the application of partial vacuums or pressures or the application of a slowly building pressure or vacuum.
U.S. Pat. No. 5,664,284 describes a hand held device that includes a trigger 24, shown in FIGS. 1 and 2, that can be manipulated by a person holding the device over a clogged drain to vary the application of pressure and vacuum. However, this hand held device has proven difficult to use in some situations. Also, the hand held device may be considered difficult to lift and position by certain users, which is especially aggravated in a household setting. Furthermore, there are practical constraints on the size, and thus the power, of the motor that creates the vacuum and pressure forces in a hand-held device.
The use of chemicals and agents to remove contaminating materials from the inside surfaces of piping systems is also well known. These chemicals and agents are used in applications from the removal of grease, scale, and bacteria to human hair and other forms of material which block flows. The limitation of these chemicals is their need to reach the surface of the pipe affected by the contamination in a uniform and effective way and stay in contact long enough to be effective. The effect of gravity alone tends to force the chemical or agent to the lower surface of the pipes leaving upper surfaces untouched and untreated.
Some contaminating materials are physically aggressive and adhere or stick to pipe surface resulting in incomplete clearing and cleaning. Mechanical methods e.g., jetters, are sometimes employed to agitate the dispensing of materials but these tend to utilize more active chemicals or agents and reduce the contact time with the contaminated surface.